Artificial thread and method of making same



H. H. PARKER ETAL Sept. 13, 1938.

ARTIFICIAL THREAD AND METHOD OF MAKING SAME Filed May 27, 1936 FIG. 1.

9 MEDPQOZ f PART OF CAKE INVENTQ k W JW on? H R M MP. M

Patented Sept. 13, 1938 ARTIFICIAL THREAD AND METHOD F MAKING SAME Harold Henry Parker and George P. Standley,

, Kenmore, N. Y., assignors, by mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware Application May 27, 1938, Serial No. 82,030

12 Claims.

This invention relates to the production of artificial threads and the like, and it pertains particularly to the manufacture of artificial threads and products produced therefrom having improved physical characteristics.

According to one method of producing artificial thread by the viscose process, the thread com prising untwisted filaments is collected on rotating bobbins (designated spin bobbins hereinafter, for convenience) and is permitted to dry in the form of a bobbin cake on the spin bobbin or other rigid insert. This system of drying sets up internal strains in the thread which are not uniform throughout the cake since'the intermediate layers of thread have greater freedom to shrink and do shrink to a considerably greater extent than the inner and outer layers of thread.

Yarn or thread which is dried under conditions which impose considerable strain has a somewhat higher'tenacity and a noticeably lower elongation than the yarn which has had greater freedom to shrink during drying.

It is not surprising therefore that when yarn so produced is afterwards converted into fabrics, cords or other products, it exhibits a non-uniform appearance and other non-uniform physical characteristics. For example, when strands 'or cords are formed from high tenacity rayonby doubling and twisting operations, the twist in the plied structure is uneven and the strength is seriously impaired since, for any given strain, there is uneven distribution of the load between the elements of the twisted structure, loose loops or helixes failing to assume any portion of the load -u ntil the other elements have become heavily loaded and perhaps even broken.

It is important that artificial threads, such as' regenerated cellulose threads produced by the viscose process, which tend to shrink on drying, thereby" setting up internal strains, be driedunder such conditions that if the thread is strained during drying, it will be strained uniformly. In order to produce a thread having substantially uniform shrinkage characteristics, substantially uniform tenacity, elongation and denier, and other roved physical characteristics, it is preferred that no non-uniform strain be imposed during drying.

It is particularly important that high tenacity, high denierjartificial thread, e. g. regenerated cellulose thread, such as is adapted to be utilized in the manufacture of cord to be'used in' the rein forcement of rubber vehicle tires and other rubber articles, possess uniform physical characteristics, e. g., uniform elongation, tenacity and den- -ier, since the useful life of cords and thelike to be used in rubber tires increases tremendously with uniformity of structure. This improvement in uniformity of structure is associated with more uniform stress-strain characteristics, .However, the uniformity of the modulus of elasticity is probably not the entire 'reason for the improvement since the new thread may be combined into a cord using threads having different moduli of elasticity while still obtaining a cord having improved tensile strength and durability.

The thread prepared by prior art cake drying methods showed a marked difference in elongation' and denier between threads taken from the inside and those taken from the outside of 'the spin package. When these threads of varying properties were combined-in a cord and the cord used in a tire, itwas comparativelyvalueless, being only approximately one-half as durable as the best cotton cord. Tire cord prepared from thread dried in accordance with the present invention, on the contrary, showed a durability,- by laboratory tests, of three or four times that of the best cotton cord.

It is an object of the present invention to produe artificial thread having improved physical properties.

A further object of the invention. relates to the production of artificial thread having substantially uniform tenacity, elongation, denier, and modulus of elasticity} A still further object comprises the production of high tenacity, high denier, artificial thread,

suitable for use in the production of cords for rubber tires and other articles, having substantially uniform physical characteristics.

Another object is to produce yarn which, in

the form of cord, will have improved durability. 1

Another object pertains to an improved process of twisting and drying, high tenacity, high den- .ier, artificial thread.

Other objects of the invention will appear here-i inafter.

Figure 1 is a. graphic illustration of a typical moisture gradient based on the composite result of anumber of bobbin cakes of artificial yarn to be dried in accordance with the principles of the present invention, the percentage moisture contents being plotted as ordinates againstthe thickness of the cake, going fromthe outside to the inside ofthe cake, the fractional thickness of the cake representing the ratio in yards in the portion of the cake referred to, with respect to the total yardage of the cake, so that the numeral 5 ture gradient such that the inner portion of the cake containsa greater moisture content than the outer portion, unwinding thread from the bobbin while the bobbin is maintained stationary or rotated very slowly and then twisting the thread on a down-twister of any type, such as, for instance, a ring twister, a cap twister or a flyer twister including the gear driven fiyer type twister, on to a spool or bobbin (hereinafter called a twister bobbin, for convenience), while maintaining an atmosphere of low relative humidity, e. g., 25% to 50% relative humidity The following examples, described with'par-- ticular reference to Figure 2 of the drawing, represent modes of applying the invention and are to be construed as illustrative and not limits-tive.

Example I Regenerated cellulose thread of 2'75 denier- 120 filament size, is produced from viscose in the usual manner and wound up at the spinning machine on 3 diameter perforated bobbins to form cakes thereon about 5" long and V in thickness.

- acid free in any suitable manner, for instance by guide 9, through the traveler II, which runs pressure, vacuum or drip treatment. Theyarn is then finished by forcing a solution containing soap, vegetable oils, gums orother similar materialsthrough the cakes. The cakes are wrung for 5 minutes at 5,000 B. P. M. and then conditioned for approximately 2 hours in air maintained at 95 F. and 32% relative humidity.

After conditloning,'the bobbins I, and thread cakes 2 thereon are placed on the deck 3 of a ring twisting machine behind the twisting bobbins l2 upon which thethread will be wound.. Each spin bobbin l is provided atits upper ends.

with a circular removable cap I having a smooth, polished edge to permit removal of the. thread without its being caught-or torn by the roughend of the bobbin. The yarn is unwound from the bobbin by drawing it vertically over the end and is passed upwardly either over a freely rotatable roller 8 or a fixed guide, preferablyv of a fine grain, unglazed porcelainymounted about 2 feet above the top of the bobbin I and thence downwardly around the positively rotated twister feed rollers I and 8, the surfaces of which are in close relationship and one of which is preferably cork covered, so as to positively draw the thread from the bobbin. The thread then through around, a ring II, and on to the spindle bobbin I! of the ring twister. The draw-oi! speed and the spindle speed are adjusted to impart '1 turns per inch of twist to the thread. These speeds may be-varied together, depending upon other conditions maintained in the twister room to the end thatthe yarn is twisted and collected at the desired moisture content. We prefer to use a thread speed of around 700 inches per minute.

Air conditions are kept asuniforrn as is practical; for instance, the air is maintainedlat a The yarn packages are then washed temperature of from 90 F. to 95 F., and at a relative humidity of from 30% to 35%. Under these conditions, with a spindle speed of 5,000 R. P. M. and a thread speed of 700 inches per minute, the yarn dries to 10-20% average moisture in the twister bobbin as it is doffed from the twister. It is observed by testing the finished thread that the twist is very uniform, that the thread has retained substantially all of its original strength, and that the quality of the thread so produced is unusually high.

Example II in thickness, after washing and finishing, are

placed end to end on a rod with preferably a cardboard or rubber gasket slid over the rodat each end, effectively sealing the space inside the bobbins against air flow. The bobbins of yarn are then placed on carriers which convey the yarn through tunnels in which air of 72% relative humidity and temperature of 95- F. is circulated. Time of conditioning is preferably around 16 hours. At the end of that time the moisture gradient throughout the cakes will be found to be substantially asset forth on the curve in Figure l, which curve indicates a preferred moisture content for the 275 denier-120 filament yarn cake of this example.

Example m vertical position so that the bottom ends of the bobbins are closed by the base of the tray and on top of the bobbins another tray or'a fiat cover is placed so that circulation of air inside but not around the bobbins is prevented. The

- trays of bobbins may then be placed in a warm room, say at 90-100 E, which room is maintained at a relative humidity of between 35% and 40% and allowed to remain there for from 3 to 5 hours. At the. end of that time, the yarn on the surface of the bobbins will be found to contain about 40-50% moisture, based onthe dry weight of the yarn, while the yarn one third of the way in and beyond will contain in the neighborhood of from loo-120% moisture.

Thesebobbins of. yarn are placed on thetwisting machine and twisted in the manner described in Example I, the room temperature being maintained at about 95 F., and the relative humidity at about 32%.

Example IV The operation is the same as in Example I except that the thread is twisted to 4 turns per inch instead of 7 turns per inch. It is necessary in this case to reduce the spindle speed to 3200 R. P. M. in order to maintain approximately the same thread speed and the same time for drying.

If the amount of twist to be imparted to the yarn is but 3 to 4' turns per inch rather than 7 turns per. inch, while maintaining the same spindle speed, we find it. advantageous to increase the travel of the thread from the untwisted yarn package to the twisted spool to as much as 15 or 20 feet, or to raise the temperature in the twisting room,or perhaps even blow a stream of warm, dry air against the thread in its travel from the spinning bobbin to the twisting bobbin.

Example V A yarn of 900 denier, 390 filament count is spun on large bobbins as mentioned in Example II.

These bobbins, after finishing, are placed on carriers or trays and subjected to air having a relative humidity of about and having a temperature of 160 F. for approximately 3 hours.

' They may then be immediately twisted or, if

greater uniformity is desired,- they may be wrapped in moistureproof material and conditioned for a suitable length of time. The cakes are then placed on the deck of'the twister and 3 turns per inch twist inserted in the yarn. Spindle speed is around 2,400 R.- P. with thread speed of around 800 inchesper minute.

The invention is particularly concerned with Y the twisting of thread having a high denier, i. e., a denier of 200 or higher. High denier thread requires the use of a down-twister, for example, a ring-twister or cap-twister. of the thread requires the use of low relative humidity in order to dry the thread uniformly during the twisting operation, the drying being accomplished in great part by the rapid ballooning of the thread which gives rise to a rapid relative movement between the thread and the air.

Preferably the thread cakeshould-be held stationary in order that it will not dry out too much before the thread is twisted on to the twister bobbin. The use of an rip-twister would impart.

rapid rotation to the yarn cake and would cause the thread to be dried to a considerable extent in the cake before being collected on the twister bobbin.

The yarn .cake, prior to twisting/should be dried under conditions which remove more moisture from the outside of the cake than from'the inside. This conditioning or-drying of the yarn cake may be accomplished in any'suitable manner. For example, the spin bobbin,havlng the bobbin cake thereon, may be whizzed about its own 'axisat a high rotational speed and may thereafter be stored in a room in which theair is maintained at a low relative humidity, e. g., 35% to 50% relative humidity, for a period of time while the bobbins are so mounted as to prevent drying of the yarn from the inside of the bobbin. Drying from the insideof. the bobbin can be prevented by plugging the ends of the individual bobbins, or by placing several of the bobbins end-to-end on along cylinder, the diam- ,eter of which is only very slightly smaller than the inside diameter of the bobbins.

- If desired, instead of storing the bobbins in av room containing low humidity air, the thread package, while still containing, for example, 150% moisture, may be placed in a tunnel drier through which high humidity air, e. g., air having 0 a relative humidity of or above, is passed through the tunnel at a controlled rate, the conditioning of the yarn proceeding to the point'of desired moisture content, the ends of the bobbin being sealed to prevent drying from the inside of the bobbin.

It is important that the untwisted yarn on the spinning bobbin be permitted, prior to the twisting operation, to dry down to not less than a certain amount on the surface of the cake to prevent a certain amount of non-uniform shrinkage taking place. The minimum moisture content tolerated on the outside of the cake will depend upon the spinning conditions and also on the denier of the thread. Under certain conditions, the amount of moisture in the surface layer The heavy denier of lower denier.

without drying the extreme inside layers of.

of the yarn cakemay be as high as 60-70%, provided that the thread on the twisting bobbin is dried down to 25% moisture or less. For instance, if the yarn to be twisted is of fine denier, e. g., 100 denier or less, and especially if the I twist to be'imparted to the thread is to be at least 7 turns and possibly more per inch and with a normal spindle speed of about 5,000 B. P. M. it is advantageous to start with untwisted yarn having as much as moisture therein, so that undue drying out of the thread will not take place during the long period of time that it remains on the twister. Except in the case of very heavy denier threads, it is normally desired that the moisture content of the thread cake on the surface of the untwisted'thread be not less than 35%. The inner portions of the cake will contain considerably more moisture than the outside layers.

In the case of very heavy denier yarns (for example 500 -to 1,500 denier and upwards) it is preferable to remove a much larger portion of the moisture in a preliminary conditioning operation prior to twisting than in the case oi yarns This should be accomplished the moisture diffuses from the middle layers to the outer surfaces, giving a more uniform moisture gradient throughout the cake.- If necessary, these two operations of drying and difiusion, can

.be repeated until the moisture throughout-the cake reaches the desired level. In the case of the higher denier yarns, the moisture in the extreme outer layers of the cake may be as lowv as 7%, the moisture content in the innermost one third of the cake being at least about 25%, the lower moisture content being desired with higher deniers, e. g., 900 denier and higher on account of the greater difliculty of drying such threads during the twisting operation. It is understood that the portion of the cake intermediate the outside and inside will likewise have a higher moisture content, for example 25% or more.

The moisture gradient throughout the cake of conditioned, untwisted yarn will, of course, be changed somewhat during the time it remains on the deck of the twister. It is desirable that this moisture content be such that as the outer layers are drawn from the spin bobbin, the newly moisture content by the time they are being unwound, as was contained in. the original outer layers of the yarn package. If the outer layers of the yarn package originally contained as much as 70% moisture, then it is desirable that the inner two thirds of the bobbin cake contain or ab0ve, e' g., -130%.

A room temperature of 80-100 F. and a relative humidity of 30-50%, maintained during the drying and twisting operations are quite satisfactory although other temperatures may be used I and humidities lower than the range mentioned exposed layers will acquire substantially the same can also be used. If .a higher. temperature is .75

used, a higher relative humidity is preferred in order that drying will not occur too rapidly, particularly on the spin bobbin, whereas when a lower temperature is used, a lower relative humidity should be maintained. The relative humidity will be maintained under 50% and preferably between and (depending to a certain extent upon the temperature of the room, upon the denier of the thread, upon the previous conditioning of the yarn, and upon the spindle speed and twist to be imparted to the yarn) in order to remove the moisture to such a point that twisting of the thread will occur when the yarn is substantially dry, e. 3., 25-50% contained moisture, based on the dry weight of the yarn, the twist thus being inserted gradually as the moisture content decreases from to spin bobbin. Or, the ,balloon and twister spoolmay be' encased in a chamber ,through which low humidity air at a higher temperature may be conducted so asto obtain rapid drying of the yarn, the room temperature being lower and its relative humidity higher if desired.

The drying of the thread may be facilitated by the use of a heated twister feed roll. The surface of the roll may thus be maintained at such a temperature as to dry the thread during its relatively short time of contact with the roll surface. This method has several possible advantages including the handling of heavy denier threads, such as 900 denier and higher, with a higher moisture content, and where a lowtwist is imparted to the thread, the thread speed being so high as to make it impractical to dry by the mere use of a conditioning step anddowntwisting. By the use of a hot roll it is possible to dry this thread and then, in the balloon, to condition it to a uniform shipping point by maintaining the proper humidity in the room, for example a relatively high humidity of While the processes of the present invention have been described with relation to the drying of bobbin spun yarn, it can be applied with suc-- cess to yarn spun in centrifugal spinning buckets, the cakes being called bucket cakes. Bucket cakes have a twist imparted to the thread by virtue of the rotation of the bucket, this twist usually being about 4 turns per inch. The present method of drying can be applied to such cakes, thereby imparting a higher degree of twisting'with less expense. .The conditioning of the bucket cakes may be along the lines discussed with relation to bobbin cakes, i. e. retarding evaporation of moisture from the inner layers,

or the outersurface of the cake may be protected by an impermeable covering so that evaporation will take place only from the inside. It is preferred that the yarn will be removed from that portion of the cake first where the moisture content is lowest and with cakes conditioned in the manner last described the yarn will beremoved first from the inside of the cake rather than from the outside as is customary.

The process of the present invention is applicable to the treatment of small bobbin cakes,

as described in Example I, or of large bobbin cakes, as described in Example II, and the cakes may be of any desired thickness.

If desired, a finish may be applied to the thread during the twisting of the thread by passing the thread in contact with a roller, wick, or the like submerged in a trough containing a finish which will impart the desired property to the yarn to prevent degradation during twisting. The trough may be disposed between the spin bobbin and the feed roller. Wipers or squeeze rolls could be used to remove excess moisture, thus facilitating drying. A dye or size can be applied in the same way.

If desired, instead of operating on gel thread, the present twisting process maybe applied with some advantage to thread which has been dried according to prior art methods and rewetted as by contact with a roller submerged in water.

instead of twisting a single thread, a plurallty of gel or rewetted yarns may be doubled and twisted together under such conditions that they are wound up on the twister spool with a moisture content no greater than 25% and preferably no greater than 15%. I Y I In case it is desired to reduce the elongation of the yarn (strand or cord) spinning tensions higher than normal may be used. For instance, in twisting 275 denier yarn, a normal tension of about 15 grams is imposed on the yarn between the feed rolls and twister spool. If the tension is raised to 30, 50 or even grams, for instance, by using a heaviertraveler in the case of ,a ring twister or by suitable adjustments in the case of a gear driven flyer type twister of the type manufactured by the Brownell Twister Company, the yarn is uniformly'stretched out and a noticeable lowering of elongation results. If desired, a suitable high tension may be uniformly applied to the yarn or strand at any point between the package on the deck of the twister and the twister spool.

By practicing the invention as set forth herein, it is possible to'produce a twisted thread that has very uniform twist, and that is unusually high in quality. Furthermore, the yarn so produced has very uniform shrinkage characteristics which make it well suited for use in woven goods or other fabrics where uniform physical properties are essential. The invention is especially suited .to the twisting of high tenacity rayon such as yarn having a tenacity of 2.5, -3- or even more grams per denier and the high quality of thread which results from this process enables us to prepare strands and cords therefrom without substantial loss in strength in the threads or filaments comprising the cord and with very uniform strand and cord twist which enables us to 'utilize to the maximum the strength contained in the individual filaments or thread.

The combination of drying and twisting as taught by this invention permits a uniform twist to be put into the thread, due to the fact that the moist thread does notslip as it passes through the feed rolls. l

By way of illustrating the advantages accruing to the drying of high denier,- high tenacity rayon used in the manufacture of cord to be used. in tires, twister drying according to the present invention of a 275 denierfilament thread results in a decrease in dry tenacity'at room temperature of 0.12 gram per denier, the thread dried in accordance with the present invention having a difference in dry elongation between the inside and the outside of the spin cake of 0.3%, whereas bobbin yarn dried in the usual manuer,-has an inside-outside difference in the elongation of 2.5%. Yarn dried according to the twister drying method of the present invention shows the same stress-strain characteristics for both the outside and the inside ofthe spin cake, whereas bobbin dried yarn dried in accordance with normal, previously 'known, drying procedures shows very different stressstrain relationships for the outside and the 'inside of the, cake.

In spite of the fact that the drying method-of the present invention causes a loss in strength, although small, in the thread, cord made therefrom is stronger than cord made from the high denier, high tenacity, regenerated cellulose thread dried on the bobbin according to previous processes. If the cord is constructed so that the yarn from the same portion of the spin cake is always together in the cord, that is outside against outside, this difference in 'tenacity' amounts to 0.4 pound. If the cord is constructed so that eight ends of yarn from the outside of the spin cake are combined with seven ends from the-inside of the spin cake, yarn dried in ac-- cordance'with the present invention produces a cord with 0.7 pound greater tenacity than the cord made from yarn dried on the bobbin by prior art methods.

The thread dried andtwisted in accordance with the present invention is admirably suited for the manufacture of plied structures, such as strands and cords. Thus, the threads produced in accordance with Examples I and II can be formed into cord by twisting five of the threads ,to 20 turns per inch in a direction opposite to that of the thread twist, three of the strands so formed being twisted to 10 turns per inch in a direction opposite to that oi the strand twist. The cord thus formed has a high twist, but is nevertheless smooth and uniform, has a higher tenacity than have cords; formed from threads produced according to prior art bobbin drying processes, and has a. useful life greatly inv excess of that of prior art cords. Degrees of twist in the threads, strands and cords other than those specifically mentioned maybe used, the specific twists mentioned being given merely by way of example.

Low relative humidity, as used throughout the specification and claims, signifies a humidity not in excess of 50%. V

"Normal room temperature, as used throughout the specification and claims, signifies a temperature of 75 F. a

"High denier, as used throughout the specification and claims, means a denier of at least 200.

relative High tenacity rayon, as used throughout the specification and claims, means rayon thread having a drytenacity at normal room tempera ture of atleast 2.5 grams per denier, obtained according to the following test:

The thread is reeled under uniform tension 1 450 meter skeins. These skeins are conditioned -for 24 hours in an atmosphere maintained at each of the abovefskeins are tested separately.

These are clamped in the tester and stretched until the yarn breaks. Both the breaking load in grams and the per cent elongation may be read directly from scales on the machine.

Grams per denier are obtained, by dividing the scale reading in grams by the denier of the. thread.

The average of 50 dry breaks on threads selected at random is considered to be the tensile stren'gth'for any given 100 pound lot of yarn.

, Dry elongation of rayon thread signifies elongation of the dry thread at normal room temperature as determined by the test given just above.

The dry strength of the strands or cordsis obtained by conditioning at 60% relative humidity and 70 F. and testing according to the A. S. T. M. procedure D i79-30. Standard, vol. II, 1930, page 1085.)

Where methods of testing other than those specifically referred to herein are used, difierent (See A. s. T. M.

numerical results may be obtained, but the relative improvement over the prior art will be of the same order, regardlessof the method of testing used. 4

fications and variations, any departure from the specific examples and'details given above which conform to the spirit of the invention are said to be included in the scope of the claims.

Thus, although the invention is especially suited for the drying and twisting of high tenacity, regenerated cellulose thread produced by the viscose process, it is also applicable to the drying and twisting of regenerated cellulose thread made by the cuprammoniu'm process, or cellulose de- .rivative threads produced by a wet .spinning process, e. g. lowly etherified cellulose thers such as glycol, ethyl or methyl cellulose, or lowly esterified cellulose acetate or other textile threads which have a tendency, to shrink during drying,

. Since the invention is capable of many modie which may be processed in accordance with this invention to produce improved twisted structures.

We claim: v

1. In the processing of wet-spun artificial thread, having a denier of at least 200, collected and washed in cake form, the steps comprising conditioning said cake of thread to impart a differential moisture content thereto, said differ ential moisture content being of such a character that the moisture content of the layers ofthread which will first .be removed from said cake is lower than that of the remaining thread layers,

and drying and twisting said thread from said conditioned cake on a down-twister whereby to obtain a twisted thread containing less than 25% moisture. 2. In the processing of wet-spun artificial thread, having a denier of at least 200, collected and washed in cake'form, the steps comprising conditioning said cake. of thread to impart a differential moisture content thereto, said differential moisture content being of such a character that the moisture content of the layers of thread which will first be removed from said cake is lower than that oi the remaining thread layers, and drying and twisting said thread from said conditionedcake on a down-twister, said drying and twisting operation being carried out in an atmosphere maintained at a relative humidity not in excess of whereby to obtain a twisted thread containing-less than 25% of moisture.

3. In the processing of wet-spun artificial thread, having a denier of at least 200, collected and washed in cake form, the steps comprising conditioning said cake thread to impart a differential moisture content thereto, said diflerential moisture content being of such a character that the moisture content of the layers of thread which will first be removed from said cake is lower than that of the remaining thread layers,

and drying and twisting said thread from said conditioned cake, on a down-twister, said drying and twisting operation being carried out in an atmosphere maintained at a relative humidity not in excess or 50% and at a temperature not less than 80 F., whereby to obtain a twisted thread containing less than .25% moisture.

4. In the processing of -regenerated cellulose ditioning said bobbinsoi thread to impart a differential moisture content thereto, saiddifleren- I tial moisture content beingof such a character I that the moisture content of the outer layers of thread on said conditioned bobbins is lower than the moisture content of the inner layers, and drying and twisting said thread from said conditioned bobbins on a down-twister whereby'to ob- 5 ,tain a twisted thread containing not less than moisture. 5.In the processing -,of regenerated cellulose thread, having a denier'ot at least 200, collected and washed on bobbins, the steps comprising conditioning said bobbins of thread to impart a differential moisture content thereto, said difierential moisture content being or such a character that the moisture content of the outer-layers o! thread on said conditioned bobbins is lower than 5 the moisture content of the inner layers, and drying and twisting said thread from said conditioned bobbins on a down-twister, said drying and twisting being carried out in an atmosphere main layers, and drying and twisting said thread from.

said conditioned bobbins on a down-twister, said drying and twisting being carried out in an atmosphere maintained at a relative humidity not in excess of and at a temperature not less than -80 'F., whereby to obtain a twisted thread containing less "than 25% moisture. 3

7.111 the process as deflnedin claim 5, the

/ step of imparting a differential .moisture' content to the bobbins, said diflerential moisture con tentgbeing of such "a character that the outer layers of thread in the conditioned bobbins have a moisturecontent of between 40% and 70%.

8. In the processing of regenerated cellulose thread, having a denier ot-at least 200, and a .thread, having a denier of at least 200, collected and washed on bobbins. the steps comprising contenacity of at least 2.5 grams per denier collected and washed on bobbins, the steps comprising conditioning. said bobbins of thread to impart a differential moisture content thereto, said differential moisture content being or such a character "5 that the moisture content of the outer layers of thread on said conditioned bobbins is from 40% toand the moisture content of the inner two-thirds of said bobbin is from 100% to 130% and. twisting said thread from said conditioned bobbin on av down-twister while maintaining the atmosphereabout the down-twister spool and the balloon at a relative humidity below 50% and at a temperature above so as to eifect the uniform drying of the thread to below 25% moisture con- 5 tent.

9. In the processing of regenerated cellulose thread, having a denier of about 275 and a filament count of about 120, collected and washed on bobbins, the steps comprising conditioning said 20 bobbins of thread to impart a differential moisture content thereto, said differential moisture content being of such a character that the moisture content of the outer layers of thread on said conditioned bobbin is from 40% to 7 0% and the. 9,5

moisture content 01 the inner two-thirds of said bobbin is from to and twisting said thread .from said conditioned bobbin on a downtwister while maintaining the atmosphere about the down-twister spool and the. balloon at a rela- -30 tive humidity below 50% and at a temperature above ,80 so asto effect the uniform drying of the thread to below 25% moisture content.

10. In the processing of regenerated cellulose thread, having a denier of about 900 and a fila- 35 ment count of about 390, collected and washed on bobbins, the steps comprising conditioning said bobbins of thread to impart a differential moisture content thereto, the diflerential moisture content being of such a character that the-mois- .4 ture content 01' the outer layers of thread on said conditioned bobbins is about 7% and the moisture content or the inner one-third of said bobbins is from-25% to 40%, and twisting said thread from said conditioned bobbins on a down-twister, 45

while maintaining the atmosphere about the down-twister spool rnd the balloon at a relative humidity below 50% and at atemperature above 80 so as to eflect a uniform drying of the thread to about 7%. I i 50 -11. A wound package of twisted regenerated,

cellulose thread having a denier of at least 200 anda tenacity ofat least 2.5 grams per denier containing not over 25% moisturev and having a diflerence in dry elongation between the inside 55 g and outside layers of said package of less than 1 2. A wound package of twisted regenerated cellulose-thread having a denier of at least 200 and a tenacity of at least 245 grams per denier. (50 containing not over 25% moisture and having a difference in dry elongation between the inside and outside layers of said package of about .3%.'

HAROLD HENRY PARKER. GEORGE P. STANDLEY. .65

CERTIFICATE OF CORRECTION. I Patent No. 2,1 o,2u7. September 1 19 HAROLD HENRE PARKER, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 6, first column, line 25, claim 1 strike out the word "net"; and that the said Letters Petent; should be read with this correction therein that the same may conform to the recoi'd of'the case in the Patent Offiee Signed and sealed. this 25thday'of October; A. D. 19 8..

Henry Van Arsdale (Seal) Acting Commissioner of Patents. 

